EMERGENCY STOP DEVICE FOR A POWER TOOL, AN ELECTRICAL POWER PACK, A POWER TOOL, SYSTEM AND METHOD

Abstract

The invention relates to an emergency stop device for a power tool comprising an electrical power contact for releasably connecting a power source to the power tool, and an emergency stop circuit connected to the electrical power contact and configured to disconnect the electrical contact from the electrical power source upon receipt of an emergency stop signal by the emergency stop circuit. The invention further relates to a power tool, a system comprising such a tool and a method of performing emergency stop of a power tool.

Claims

1-10. (canceled)

11. An emergency stop device for a power tool, the emergency stop device comprising: an electrical power contact for releasably connecting a power source to the power tool; an emergency stop circuit connected to the electrical power contact and configured to disconnect the electrical power contact from the power source upon receipt of an emergency stop signal by the emergency stop circuit; a negative and a positive electrical power contact; and at least a first relay for disconnecting the positive electrical power contact from the power source and a second relay for disconnecting the negative electrical power contact from the power source.

12. The emergency stop device according to claim 11, further comprising a wireless communication device for receiving the emergency stop signal.

13. The emergency stop device according to claim 11, in the form of a separate unit connectable to an electrical power source.

14. The emergency stop device according to claim 13, wherein the electrical power source is a separate power pack for the power tool.

15. An electrical power pack for a power tool in the form of an integrated unit comprising an electrical power source, and the emergency stop device according to claim 11 integrated in the power pack.

16. A power tool comprising a tool drive unit and the emergency stop device according to claim 11, or an electrical power pack for a power tool in the form of an integrated unit comprising an electrical power source, and the emergency stop device according to claim 11 integrated in the power pack, wherein the power pack is connected to the power tool for powering the tool drive unit, and wherein electrical power from the power pack is disconnected upon receipt of an emergency stop signal.

17. A system comprising a plurality of power tools according to claim 16, and wherein the plurality of power tools are connected to a common emergency stop bus circuit such that, when an emergency stop signal is transmitted through the common emergency stop bus circuit, each power tool connected to the bus initiates an emergency stop.

18. The system according to claim 17, further comprising emergency stop buttons and/or sensors which are configured to indicate a fault condition, communicating with the common emergency stop bus circuit.

19. The system according to claim 17, wherein each power tool of the plurality of power tools includes a separate power pack and a charging connection for continuously charging each separate power pack.

20. A method of performing emergency stop of a power tool according to claim 16, comprising the step of, upon receipt of an emergency stop signal by the emergency stop circuit, disconnecting the electrical power source from the electrical power contact means, thereby performing an emergency stop of the power tool.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0028] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

[0029] FIG. 1 shows a power tool and a power pack for a power tool, according to an embodiment of the invention.

[0030] FIG. 2 shows a power tool with a power pack and an emergency stop device according to another embodiment of the invention.

[0031] FIG. 3 shows a power tool and a power pack for a power tool, according to a further embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

[0032] In the following, a detailed description of an electrical power pack and a power tool according to embodiments of the invention is presented.

[0033] In FIG. 1 an emergency stop device 1 in the form of an electrical power pack is shown, for connection to a power tool 2. The power tool is shown with the power pack physically disconnected but they form a physically connected unit during operation of the power tool. The power tool is shown as a outrunner for tightening nuts in an assembly station, but screwdrivers, drilling tools, cutting tools, grinding tools, riveting tools, routing or sanding tools and the like are equally well suitable.

[0034] The power tool comprises a body comprising a drive unit 7, e.g. a rotating electrical motor for driving a rotatable tool head 9 of the power tool. The power tool may be controlled by an actuation means, e.g. in the form of a pistol grip 10 to control the actuation of the drive unit. Alternatively the tool is remotely actuated. The body of the power tool comprises electrical contacts in the form of a negative 8 and a positive 8′ electrical contact for receiving electrical power from the power pack 1.

[0035] The electrical power pack 1 forms an integral unit that is connectable to the power tool. It comprises an electrical power source such that in the form of a chargeable battery or a supercapacitor. The interface for connecting the power pack to the main body of the power tool comprises a negative 4 and a positive 4′ electrical contact for connecting the power source to the power tool. Optionally, the power pack may be connected to electrical mains for continuous or intermittent charging, via charging circuit 16 and cable 17.

[0036] The power pack comprises an emergency stop circuit 5 that comprises means for disconnecting the electrical contacts from the electrical power source upon receipt of an emergency stop signal, in the form of a set of relays physically disconnecting the negative 4 and the positive 4′ electrical contacts from the power source. The power pack further comprises a communication circuit for receiving an emergency stop signal from an external control unit. The communication circuit may be a wireless communication circuit for receiving an emergency stop signal over a wireless communication network, or connected to an emergency stop bus circuit via the cable 17. The emergency stop circuit is configured to open the relays and thus physically disconnect the electrical contacts from the power source upon receipt of an emergency stop signal from the communication circuit,

[0037] During operation of the power tool, the drive unit of the tool is actuated, e.g. to fasten a fastener such as a nut. The drive unit is then powered by the power source of the power pack.

[0038] However, when an emergency event is detected and the emergency stop circuit receives an emergency stop signal, the emergency stop circuit disconnects the electrical contacts from the power source, thus disconnecting the power to the drive unit of the power tool. Thereby the power to the power tool may be disconnected immediately upon an emergency stop event even for a power tool powered by a power pack.

[0039] In FIG. 2 an emergency stop device 1′ in the form of a separate unit which is connectable to an existing power pack 3 of a power tool. The emergency stop device comprises electrical contacts 4, 4′ for connection to electrical contacts 8, 8′ on the body of the power tool, and electrical contacts 14, 14′ for connection to electrical contacts 15, 15′ of the existing power pack 3 of the tool. Thus the emergency stop device forms a separate unit 1′ placed, electrically and mechanically, between the power pack 3 and the power tool. The emergency stop device 1′ comprises an emergency stop circuit 5 and a communication circuit 11 as described in relation to FIG. 1. The advantage of this solution is that existing pairs of power tools and power packs may be provided with the additional emergency stop functionality. The power tool may be configured to read out the identity of the power pack and the emergency stop circuit connected to the tool, to pair its operation to the identified power pack and the emergency stop circuit and to prevent operation if the identity of the power pack and/or emergency stop circuit deviates from the paired condition, or is missing.

[0040] FIG. 3 shows an emergency stop device 1″ in the form of an electrical power pack, similar to what is described in relation to FIG. 1. The device differs from what is previously described in that a wireless communication circuit 11′ is included in the body of the power tool itself and the emergency stop signal received by the emergency stop circuit via a communication interface in the form of a pair of contacts 12, 13 between the power tool and the power pack. Thereby the emergency stop device does not need to include a wireless communication circuit in each device, but may use the wireless communication circuit in the power tool.

[0041] Typically a power tool as disclosed herein is used in a system comprising a plurality of power tools, such as in a fixture comprising one or more fixtured tools or spindles. The power tools of the system are connected to a common emergency stop bus circuit. Throughout this bus circuit, emergency stop signals may be transmitted upon an emergency stop event, such that each power tool connected to the bus initiates an emergency stop. The system typically comprises one or more emergency stop buttons and/or sensors which are configured to indicate a fault condition, communicating with the common emergency stop bus circuit. Thereby, upon actuation of the one or more emergency stop buttons and/or indication of a fault condition by the sensors, an emergency stop signal is transmitted through the bus circuit to stop all tools and other machines connected to the common emergency stop bus circuit.